ABSTRACT
BACKGROUND: The National Institute of Standards and Technology (NIST) has produced over 40 botanical dietary supplement Standard Reference Materials® (SRMs) and reference materials (RMs) with values assigned for chemical markers and/or active compounds. Although environmental accumulation or inadvertent introduction of toxic elements (arsenic, cadmium, lead, and mercury) is a potential source of exposure in botanical dietary supplement products, the majority of the dietary supplement SRMs/RMs do not have values assigned for the four major toxic elements. OBJECTIVE: To determine As, Cd, Pb, and Hg content in the current inventory of NIST botanical dietary supplement SRMs/RMs. METHODS: Fifteen SRMs/RMs suites of plant part, extract, and finished products [i.e., solid oral dosage form (SODF)] were analyzed for As, Cd, Pb, and Hg using nitric acid microwave-assisted digestion followed by quantification using inductively coupled plasma-mass spectrometry. RESULTS: Results for control samples were in good agreement with certified values indicating that the analyses of 38 individual botanical SRMs/RMs were in control. Characterization of linked plant/extract SRMs/RMs derived from the same source materials demonstrated that while extraction processes can often yield extracts with lower toxic element content for Hg or As, it is also possible for mass fraction levels to remain unchanged or even increase following extraction. CONCLUSION: The results fill significant knowledge gaps in toxic element content ranges for SRMs/RMs where no NIST assigned values existed, in particular for Hg content and for extract and SODF matrices. With comprehensive toxic element content now available, researchers can better select appropriate dietary supplement SRMs/RMs for use as controls in the analysis of dietary supplement ingredients and products. HIGHLIGHTS: Results for As, Cd, Pb, and Hg are reported for 38 dietary supplement SRMs/RMs including 6 suites of plant, extract, and SODF and 9 pairs of plant and extract from the same batch of plant material.
ABSTRACT
Background: The performance of U.S. Food and Drug Administration (FDA) Elemental Analysis Manual (EAM) 4.13 method (Inductively Coupled Plasma-Mass Spectrometric Determination of Iodine in Food Using Tetramethyl Ammonium Hydroxide Extraction) was tested in an interlaboratory study. Objective: The aim of the study is to demonstrate that the FDA EAM method 4.13 is applicable for the analysis of food and multivitamins. Methods: Six collaborators participated in the study using four different models of inductively coupled plasma-mass spectrometry instruments. The method evaluation included determination of the limits of detection and quantification, analysis of National Institute of Standards and Technology standard reference materials (SRMs), unknown samples, blinded SRMs, and fortified analytical portions by all six collaborators. The samples were chosen to represent all sectors of the AOAC food triangle and additionally included pet food and multivitamin tablets. Results: The repeatability and reproducibility ranges were 1.8-11.4% and 3.6-13.7%, respectively; the calculated HorRat values were in the 0.17-1.18 range; and 174 of 175 SRM analyses had z-scores <2 and fortified analytical portion samples with recoveries of 102-105%, indicating acceptable method performance. Conclusions: The study supports a Level Three Multilaboratory Validation according to FDA Food and Veterinary Program Guidelines performed by six collaborators using six certified reference materials and nine unknown samples. Highlights: The method is applicable for quantification of the total extractable iodine in food and multivitamin dietary supplements.